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Environ Monit Assess
DOI 10.1007/s10661-010-1678-y

Carbon footprint: current methods of estimation
Divya Pandey · Madhoolika Agrawal ·
Jai Shanker Pandey

Received: 7 April 2010 / Accepted: 23 August 2010
© Springer Science+Business Media B.V. 2010

Abstract Increasing greenhouse gaseous concentration in the atmosphere is perturbing the environment to cause grievous global warming and
associated consequences. Following the rule that
only measurable is manageable, mensuration of
greenhouse gas intensiveness of different products, bodies, and processes is going on worldwide,
expressed as their carbon footprints. The methodologies for carbon footprint calculations are still
evolving and it is emerging as an important tool
for greenhouse gas management. The concept of
carbon footprinting has permeated and is being
commercialized in all the areas of life and economy, but there is little coherence in definitions
and calculations of carbon footprints among the
studies. There are disagreements in the selection
of gases, and the order of emissions to be covered
in footprint calculations. Standards of greenhouse gas accounting are the common resources

D. Pandey · M. Agrawal (B)
Laboratory of Air Pollution and Global Climate
Change, Ecology Research Circle, Department
of Botany, Banaras Hindu University,
Varanasi 221005, India
J. S. Pandey
National Environmental Engineering Research
Institute (NEERI), Nagpur 440020, India

used in footprint calculations, although there is
no mandatory provision of footprint verification.
Carbon footprinting is intended to be a tool to
guide the relevant emission cuts and verifications,
its standardization at international level are therefore necessary. Present review describes the prevailing carbon footprinting methods and raises the
related issues.
Keywords Carbon footprint · Direct emissions ·
Embodied emissions · Greenhouse gases

The Intergovernmental Panel on Climate Change
(IPCC) in its fourth assessment report has
strongly recommended to limit the increase in
global temperature below 2◦ C as compared to preindustrial level (i.e., measured from 1750) to avoid
serious ecological and economic threats. A rise in
temperature by 0.74◦ C has already been recorded
and hence climate scientists are focusing on an
urgent action to curb global warming (IPCC 2007;
Kerr 2007). The imbalances caused in natural systems due to warming are already being signaled
in the form of extreme weather events and climate change. The mountainous snow cover, permafrost, and glaciers are melting and Greenland,
Antarctic, and Arctic ice packs are experiencing a

Environ Monit Assess

negative mass balance causing the sea level to rise
at a rate of 3 mm year−1 (Kerr 2006; Rignot and
Kanagaratnam 2006; IPCC 2007). Owing to such
complex changes in natural phenomena, it has
been projected that 1–2 billion additional people
will be under water stress, crop productivity in
mid-latitudes will suffer loss, and wildlife and
biodiversity will be threatened (Kerr 2007). On
social forefront, developing and poor countries
are at immediate and disproportionately high risk
of being adversely affected by global warming and
thus the “MILLENNIUM development goal” of
eradicating poverty may be compromised (UNDP
2007). “The world is running short of time and
option” at social and economic front in view of
high risks related with global warming and climate
change (Stern 2006). Strong and immediate local
to international actions are thus needed to stabilize emissions in a justified manner. As the understanding of the science and consequences of global
warming grew, the concern for preventing disastrous climate change led to a substantive action
in the form of endorsement of “Kyoto protocol”
in 1997 which requires developed economies or
economies in transition listed in its annexure I to
reduce their collective emissions of six important
greenhouse gases (GHGs) namely carbon dioxide
(CO2 ), methane (CH4 ), nitrous oxide (N2 O), set
of perfluorocarbons, and hydrofluorocarbons by
at least 5.2% as compared to 1990 level during the
period 2008–2012 (UN 1998). The gases covered
under Kyoto protocol are referred collectively as
“Kyoto gases” (WRI/WBCSD 2004). This protocol, however, has not received equal support from
all the nations and some did not ratify it giving reasons that their economies may suffer loss. However, a critical review over impacts of acting or not
acting against climate change carried out by Stern
(2006) led to the conclusion that “the benefits
of strong early action considerably outweigh the
costs.” It was predicted that not acting immediately will cost at least 5% of global gross domestic
product (GDP) loss annually while annual investment equivalent to 1% of global GDP may help
in limiting temperature rise below 2◦ C. Otherwise it would be impossible to revert the changes.
Emissions of Kyoto gases need to be cut by 25%
below the current level by 2050 so that the growth
of countries is not compromised.

Greenhouse gas sources
Rapid rise in global temperature is due to the “enhanced greenhouse effect” (i.e., the greenhouse
effect additional to the natural) due to human induced release of GHGs into the atmosphere. Not
all GHGs have equal capacity to cause warming
but their strengths depend on radiative forcing
it causes and the average time for which that
gas molecule stays in the atmosphere. Considering these two together, the average warming it
can cause, known as ‘global warming potential’
(GWP), is calculated mathematically and is expressed relative to that of CO2 . Therefore, unit of
GWP is carbon dioxide equivalent (CO2 -e).
Important contributors to global warming are
Kyoto gases, whose emissions increased by 70%
during 1970–2004 (IPCC 2007). In addition to
these six gases, the members of chlorofluorocarbons family bear very high GWP, but since
their emissions have been controlled successfully
under Montreal protocol, they are no longer a
problem. Tropospheric ozone and black carbon
have also been found to warm the troposphere.
The rates of increment in GHG concentrations
are extraordinarily high, far exceeding the natural
range as evident from geological and ice core
studies (IPCC 2007). The biggest share of these
GHGs comes from fossil fuel combustions in the
form of CO2 (58.6%). Next come CH4 and N2 O
contributing to 14.3% and 7.9%, respectively, to
total collective CO2 -e. Major sources of these two
gases are the agricultural systems (IPCC 2007).
In order to comply with 2◦ C target, the atmospheric stock of GHGs needs to be stabilized
below 550 ppm in terms of carbon dioxide equivalents, of which 430 ppm has been attained in
2007 (Page 2008). Therefore GHG inventories
are going on all over the world and every possible method to control them are being recognized and evaluated. As the climate change issues
became prominent on political and corporate
agenda, general public especially in developed
countries started recognizing their responsibility towards taking action against global warming (Goodall 2007). These concerns and media
have provided tremendous popularity to quantification of the contribution of various activities
to global warming usually represented in terms of

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“carbon footprint”. However, information available on carbon footprinting beset with uncertainty
and inconsistency (Schiermeier 2006; Wiedmann
and Minx 2007; Kenny and Gray 2008; Padgett
et al. 2008). The objective of the present review
is to systematically analyze the relevant available
information on global warming, GHG emissions
and characteristics, carbon footprinting concepts,
calculation of carbon footprints, methodology
followed for estimation, and uses of this by
general public, corporate sector, industries, and

Concept of carbon footprint
Origin of carbon footprint can be traced back to
as a subset of “ecological footprint” proposed by
Wackernagel and Rees (1996). Ecological footprint refers to the biologically productive land
and sea area required to sustain a given human
population expressed as global hectares. According to this concept, carbon footprint refers to the
land area required to assimilate the entire CO2
produced by the mankind during its lifetime. In
due course of time as the global warming issue
took prominence in the world environmental
agenda, use of carbon footprint became common independently, although in a modified form
(East 2008). The concept of carbon footprinting
has been in use since several decades but known
differently as life cycle impact category indicator global warming potential (Finkbeiner 2009).
Therefore, the present form of carbon footprint
may be viewed as a hybrid, deriving its name from
“ecological footprint”, and conceptually being a
global warming potential indicator. There are few
studies that report carbon footprint in terms of
global hectares notwithstanding the modern nexus
about it (Browne et al. 2009). Besides its widespread favorable public reputation as an indicator
of contribution of an entity to the global warming,
there are confusions over what it exactly means
(Wiedmann and Minx 2007; East 2008; Finkbeiner
2009; Peters 2010). It is also remarked that the
scientific literature on the subject is scarce and
the most studies have been carried out by private
organizations and companies predominantly due
to their business sense rather than their environ-

mental responsibility (Kleiner 2007; Wiedmann
and Minx 2007; East 2008). Other terms used
associated or sometimes as a synonym of carbon
footprint in the available literature are embodied
carbon, carbon content, embedded carbon, carbon
flows, virtual carbon, GHG footprint, and climate
footprint (Wiedmann and Minx 2007; Courchene
and Allan 2008; Edgar and Peters 2009; Peters
2010). There is little uniformity in the definitions
of carbon footprint within the available literature
and studies (Wiedmann and Minx 2007). Based on
their survey, Wiedmann and Minx (2007) defined
that the carbon footprint is a measure of the exclusive total amount of carbon dioxide emissions
that is directly and indirectly caused by an activity
or is accumulated over the life stages of a product.
A new term “climate footprint” was proposed as
a comprehensive GHG indicator, i.e., if all the
GHGs originating from within the boundary are
quantified. However, new studies and methods
followed for carbon footprint calculation, suggest
including other GHGs as well, apart from only
CO2 (Office of sustainability and environment,
City of Seattle 2002; Kelly et al. 2009; Eshel and
Martin 2006; Bokowski et al. 2007; Ferris et al.
2007; T C Chan Center for Building Simulation
& Energy Studies/Penn Praxis 2007; Garg and
Dornfeld 2008; Good Company 2008; Johnson
2008, Edgar and Peters 2009; Browne et al. 2009).
There is a lack of uniformity over the selection
of direct and embodied emissions. Direct emissions are those that are made directly during the
progress of a process. As an example, CO2 released during combustion in a gasoline fired industrial boiler is a direct emission. On the other
hand in electrically heated boiler, no direct emissions will be observed. But if the electricity used
in the boiler was generated in a thermal power
plant, the amount of CO2 released in generation and transmission of the units of electricity
consumed in the boiler is referred as the embodied or indirect emission. It becomes complex
to include all possible emissions and thus most
studies report only direct or first order indirect
emissions (Carbon Trust 2007b; Wiedmann and
Minx 2007; Matthews et al. 2008b). In absence
of consistencies among selection of characteristic
properties of carbon footprint viz. gases selected
and boundaries drawn for the carbon footprint

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calculations by different organizations vary significantly (Wiedmann and Minx 2007; Kenny and
Gray 2008; Padgett et al. 2008). Since carbon
footprint is associated with money transactions in
form of taxes, carbon offsets, or increase/decrease
in consumer choices, consistent carbon footprint
calculations are essential to facilitate comparisons.
In spite of prevailing differences among the calculations, the CO2 equivalent (CO2 -e) mass based
on 100 years global warming potential has been
accepted as reporting unit of carbon footprint
(WRI/WBCSD 2004; Carbon Trust 2007b; BSI
2008). Hammond (2007) and Global Footprint
Network (2007) hold the opinion that “footprints
are spatial indicators”. Hence, the term commonly called as carbon footprint should precisely
be called as “carbon weight” or “carbon mass”
(Jarvis 2007). But CO2 -e mass has been promoted
as unit of carbon footprint due to convenient
calculations and wide acceptance (Lynas 2007).
Therefore carbon footprint may be defined as,
“the quantity of GHGs expressed in terms of
CO2 -e, emitted into the atmosphere by an individual, organization, process, product, or event from
within a specified boundary”. The set of GHGs
and boundaries are defined in accordance with the
methodology adopted and the objective of carbon
footprinting as discussed later in this review.

Fig. 1 Carbon footprint
per capita in different
classes on countries based
on degree of development
(based on UNDP 2007)

Importance of carbon footprinting
Carbon footprint, being a quantitative expression
of GHG emissions from an activity helps in emission management and evaluation of mitigation
measures (Carbon Trust 2007b). Having quantified the emissions, the important sources of
emissions can be identified and areas of emission reductions and increasing efficiencies can be
prioritized. This provides the opportunity for environmental efficiencies and cost reductions. Reporting of carbon footprint to the third party or
disclosure to the public is needed in response to
legislative requirements, or carbon trading or as a
part of corporate social responsibility, or for improving the brand’s image (Carbon Trust 2007b;
L.E.K. Consulting LLP 2007).
Legislative actions have been taken to quantify
and reduce carbon footprint of cities and organizations and it is playing an important role in policy
making (Office of sustainability and environment,
City of Seattle 2002; Courchene and Allan 2008;
Good Company 2008). USA has made it mandatory to keep register of emissions from firms and
companies under ‘Consolidated Appropriations
Act, 2008’ (Rich 2008). EU has also taken lead
in formulating legal bindings for reduction in
emissions embodied in aviation. California capped

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Table 1 Carbon footprints of some entities and the tiers covered
S. no.



Carbon footprint
(ton CO2 -e)



World’s per capita

4.5 in 2004

UNDP (2007)


Per capita national footprint

Based on emissions from
fossil fuel consumption,
gas flaring, and cement
Based on emissions
embodied in construction,
shelter, food, clothing,
manufactured products,
mobility, service, and trade

Edgar and Peters (2009)


United Nations Climate
Change Conference, 2008 in
Poznan´ (an estimate carried
out by the Polish government)

In 2001
USA: 2.86 × 10
Brazil: 4.1
France: 1.31 × 10
India: 1.8
China: 3.1
Malaysia: 4.2
Zimbabwe: 2.0
Approx. 1.3 × 104


The World Bank’s energy portfolio
Assumption: all reserves activated
with the World Bank assistance
will be extracted and burned and
projects operate at full capacity
for a lifetime of 20 years. All end
use emissions are calculated
Methodology adopted: IPCC tier I
approach (i.e., using a default
emissions factor)


University of British Columbia
(Point grey campus)


University of Pennsylvania


Books and documents in
engineering library,
University of California

Tier I: air travel and local
Tier II and III (no clear
demarcation between the
tiers available): hotels,
meeting rooms
Fossil fuel-based extraction,
production, and energy
generation projects
supported by The
World Bank
Excluded: other
emissions-intensive sectors,
transport, infrastructure,
and industry, or additional
emissions from fossil fuel
production, like gas flaring,
transmission lines for
electricity, projects, and
specific fossil fuel projects
for which data have not
been disclosed publicly
Tier I: heat, commuter
traffics, transit, and flights
Tier II: emissions embodied
in electricity
Tier I: natural gas and
Tier II: energy consumption
through the use of steam,
chilled water, and
Tier III: agriculture, solid
waste disposal, and
Tier I: travel of labors and
business trips
Tier II: embodied GHGs in
energy, electronic
equipments, and books
Tier III: not defined

UNFCCC (2008),

5.353 × 109 in 2001
8.23 × 108 in 2008

Craeynest and
Streatfeild (2008)

8.2750 × 104

Ferris et al. (2007)

3.0 × 105

TC Chan center for
building simulation/
Penn Praxis (2007)

5.8526×109 year−1

Garg and Dornfeld

Environ Monit Assess
Table 1 (continued)
S. no. Event/product/organisation


Carbon footprint
(ton CO2 -e)




2.154 × 107
in year 2005

USDoE (2005)


The City of Vancouver, Canada

Tier I: ground and air
Tier II: electric utilities
Tier III: not covered
Tier I: vehicle fleet, diesel
and natural gas
consumption, and
Tier II: electricity
Tier III: all other indirect
sources of greenhouse
gas emissions that may
result from city activities
or originate from sources
owned or controlled by
others, such as from the
production of goods
purchased by the city,
emissions from land-filled
solid waste, and employee’s
personal commuting habits
Tier I: fuel consumption
associated with
transportation, electricity
generation, and city heating
Tier II: significant embodied
GHG emissions in
electricity, infrastructure,
and city heating
Tier III: all other emissions
those are under direct
influence or control of the
Tier I: CO2 embodied in
fuel use in houses and
personal vehicles
Tier II and III: CO2
embodied in personal
aviation, goods and
Tier I: fuel use in houses and
personal transportation
Tier II and III: personal
aviation, goods, and

4.1983 × 107
in year 2006

Good company (2008)


The city of Seattle, USA


Average household in UK


Household in UK under reduced
consumption scenarios


4.1013 × 107
in year 2007

7.013 × 106
in year 2000

Office of Sustainability
and Environment,
City of Seattle (2002)

Approx. 5.5 × 102

Druckman and Jackson

Couple parents with
Druckman and Jackson
four children:
approx. 3.5 × 10,
couple parents with
one child: approx.
2.125 × 10, single
pensioner: approx. 7.5
Wildfires in the continental USA, (Tiers cannot be defined well) 2.93 × 108
Wiedinmyer and Neff
excluding Washington D.C.
Based on CO2 released
each year
during forest fires in US
continent averaged over

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Table 1 (continued)
S. no.



Carbon footprint
(ton CO2 -e)



Hurricane Katrina on US gulf coast

3.85 × 108

Chambers et al. (2007)


FIFA world Cup 2006

1.0 × 105

Bellassen and Leguet


Road freight transport in Britain
forecast (based on CO2 only)

1.93 × 107
forecast for 2020:
1.74 × 107

Piecyk and McKinnon


Per capita carbon footprint of
metropolitan cities

Average of 100
metropolitan cities:
2.24 for 2005 US
average 2.6 for

Brown et al. (2009)


Chlor alkali plant

4.358 × 103
per month

Tjan et al. (2010)


Tongkat Ali extract production

1.37 × 10 per month

Tjan et al. (2010)


Average balanced diet in India

(Tiers cannot be defined well)
Based on CO2 released due
to biomass loss due to
Tier I: onsite fuel
consumption related to
construction of stadiums,
travel within the country,
and temporary facilities
Tier II: electricity
consumption at the
stadiums, temporary
facilities and those used
for accommodating visitors
Tier III: not defined
Tier I: fuel consumption,
projected change in fuel
efficiency, projected
change in carbon intensity
of fuel, loading factor,
road quality
Tier I: transportation
systems. Emissions from
commercial buildings,
industry, and other modes
of transportation such as
planes, transit, and trains
have been omitted
Tiers II and III: not clear
but urban morphology
and policy interventions
have been included
Tier I: fuel consumption in
boiler and transportation
of raw materials
Tier II: electricity
Tier III: not undertaken
Tier I: fuel consumption in
boiler and transportation
of raw materials
Tier II: electricity
Tier III: not undertaken
Tier I: fuel consumption in
Tier II: transportation

Vegetarian adult male:
7.23 × 10−4
Vegetarian adult
female: 5.83×10−4
Non vegetarian adult
male: 1.031 × 10−3
Non vegetarian adult
female: 8.918×10−4

Pathak et al. (2010)

Tier III: raw material
production (agricultural
practices), processing

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Table 1 (continued)
S. no.



Carbon footprint
(ton CO2 -e)



Reduction in carbon footprint of
surgical scrub through change in
tap design in an average hospital

Tier I: not applicable
Tier II: electricity
consumption in water
Tier III: tap design,
scrubbing time, and
temperature of water

1.4 × 104 /year

Somner et al. (2008)

the GHG emissions from major industries and
put a moratorium on import of non-conventional
vehicular fuels unless its carbon footprint is less
than that of petroleum-derived fuel (Courchene
and Allan 2008). California Global Warming
Solution Act, 2006 is aimed at bringing the emissions of California to the level of 1990 by 2020
(Capoor and Ambrosi 2009). The UK Government through the Low Carbon Transition Plan,
2009 instigates households to contribute towards
building a low carbon future (Department of
Energy and Climate Change 2010). Most of the
organizations and almost all personal carbon footprinting attempts have been observed to head
towards reducing the emissions or offsetting the
footprints through buying carbon credits, or other
control measures. Besides policy matters, carbon
footprint has got an enormous importance for
business. The corporate world has sensed a carbon constrained economy in near future (Kleiner
2007). Hence a rush to calculate the carbon footprint and to cut down the emissions has begun
worldwide so as to take competitive advantage
(Kleiner 2007). It is proved by the fact that number of companies participating in CDP increased
from 383 in 2008 to 409 in 2009 (CDP 2009). In
a survey conducted by L.E.K. Consulting LLP
(2007), it was found that 44% consumers preferred to buy the products, which provided the
information about their carbon footprints, while
43% were willing to pay more for the products
with relatively low carbon footprint. Hence the
corporate sector has responded in a big way. With
growing awareness regarding climate change, a
remarkable concern has grown in individuals over
their responsibility of contributing to the emissions of GHGs. This has led to the surge of per-

sonal carbon footprinting facilities (consultancies
and online calculators) particularly in developed
countries (Padgett et al. 2008; Kenny and Gray
2008). After footprint calculation, they offer to
offset the footprint by tree plantation, supporting forestation, and renewable energy resources
(Murray and Day 2009) and for this reason, a
dramatic growth in voluntary carbon market has
been reported since 1989 (Hamilton et al. 2007).
Decrease in fossil-fueled transport systems can be
achieved through propensity to walk and use bicycles as a behavioral change in individuals (Frank
et al. 2010).
In addition to its business importance, carbon
footprint has been used as an indicator of the
impact of lifestyle of a citizen of a country on carbon emissions. The UNDP (2007) and Edgar and
Peters (2009) published country wise per capita
carbon footprint, a convenient way to compare
contributions of countries, cities, and sectors towards global warming. Figure 1 represents per
capita carbon footprint for different classes of
countries based on the degree of development.
It is clear that high income countries leave the
biggest footprint while it is substantially low for
developing countries. Carbon footprints are now
used as an important indicator of event management (London 2012 Sustainability Plan 2007).
Studies on the impact of natural and semi-natural
systems quantitatively in terms of carbon footprint
are reported (Chambers et al. 2007). It may help
to compare natural verses anthropogenic impacts
on the environment. Hence we see that hardly
there may be any entity which cannot be a candidate to carbon footprinting. Table 1 shows some
of the entities for which carbon footprint has been

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Calculation of carbon footprint
For calculating carbon footprint, the amount of
GHGs emitted/removed or embodied in life cycle
of the product has to be estimated and added. Life
cycle includes all the stages involved for a product
such as its manufacture right from bringing of
raw material to final packaging, distribution, consumption/use, and to the final stages of disposal.
Analysis of life cycle therefore is also called as
‘cradle to grave analyses’. Life cycle assessment
(LCA) produces complete picture of inputs and
outputs with respect to generation of air pollutants, water use and wastewater generation, energy consumption, GHGs emitted, or any other
similar parameter of interest and cost–benefit initiatives. This assessment is often called as environmental LCA. For carbon footprinting purpose,
LCA estimates the GHGs emitted/embodied at
each identified step of the product’s life cycle,
technically known as GHG accounting. Standards
and guidance are available for GHG accounting.
Common resources are:
1. GHG protocol of World Resource Institute
(WRI)/World Business Council on Sustainable Development (WBCSD): there are two
standards, (1) A Product Life Cycle Accounting and Reporting Standard, and (2)
Corporate Accounting and Reporting Standard: Guidelines for Value Chain (tier III)
Accounting and Reporting. It provides sectorspecific and general calculation tools and
deals with quantification of GHG reductions
resulting due to adoption of mitigation methods in its Project protocol. It forms basis for
most GHG accounting guidelines including
ISO 14064 (parts 1 and 2) (WRI/WBCSD
2004, 2005).
2. ISO 14064 (parts 1 and 2): it is an international
standard for determination of boundaries,
quantification of GHG emissions, and removal. It also provides standard for designing
of GHG mitigation projects (ISO 2006a, b).
3. Publicly Available Specifications-2050 (PAS
2050) of British Standard Institution (BSI):
it specifies the requirements for assessing the
life cycle GHG emissions of goods and services (BSI 2008).

4. 2006 IPCC guidelines for National Greenhouse Gas inventories: all anthropogenic
sources of GHG emissions are classified into
four sectors—energy, industrial process and
product use, agriculture, forestry and other
land use, and waste. 2006 guidelines are an
updated version of earlier 1996 guidelines.
All countries that are signatory to UNFCCC
and committed to prepare, update, and communicate their national GHG emissions/
removal inventories following these guidelines. Therefore emission/removal inventories
of the countries are comparable. UNFCCC
however has not yet made it compulsory to
use 2006 guidelines and hence most of the
nations are still following 1996 guidelines.
5. ISO 14025: it is a standard for carrying out
6. ISO 14067: a standard on carbon footprinting
of products is under development.
Some countries have developed their own GHG
accounting guidelines such as Department of
Food and Rural Affair (DEFRA) and Carbon
trust in United Kingdom and Environmental Protection Agency (EPA) in USA. Registries and
consultancies like World Wildlife Fund Climate
Servers, California Climate Registry (USA), The
Climate Registry (USA), etc. have formulated
their own methodologies based on these guidelines. Almost all of these newly developed guidelines and standards direct accounting for the
GHGs emitted during the manufacture, use and
disposal of the product, entity, or event and
referred to as complete LCA.
Life cycle assessment
Each stage of the life cycle of any product or
event is linked to other secondary stages, each of
which may further be linked to others and so on.
Covering all the associated steps, the boundary
may go on expanding to become too complex to
be analyzed. Selection cradle and grave should
therefore be done appropriately depending on
the objective of the assessment as well as on the
availability of data.
Approaches to perform LCA for GHG estimation are (1) “Bottom up” or “process analysis

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(PA)”; and (2) “top down” or “input–output analysis (IO)” (Wiedmann and Minx 2007; Matthews
et al. 2008a). In bottom up approach, the emission sources are broken down into different categories for convenient quantification. This method
is more accurate for small entities, but it becomes
too complex for large firms which cover more
than second order emissions thus underestimating
the actual footprint (Lenzen 2001; Wiedmann and
Minx 2007). It is useful in identification of area
of process improvement (Green Design Initiative
Top down approach makes use of economic
input–output (EIO) model extended to accept
and perform operations on environmental variables for calculations of carbon footprint (Green
Design Initiative 2008). Inputs and outputs are
represented in the form of matrix, with inputs
required to produce a unit product represented
in respective row. The inputs–outputs matrix can
be represented in the form of following equation
(Miller and Blair 1985):
x = (I + A + A × A + A × A × A + . . .)
y = (I − A)−1 y,
where I is identity matrix, y is vector of desired
outputs, A, A × A, A × A × A, ......... are the
first, second, and so on level supply chains to
produce product y. In this mathematical procedure, extension of boundary is easy and chances
of double counting are minimized. Basic algebraic
operations can clearly indicate the changes in outputs corresponding to changes in one or more
variables. Entire economic system can be put as
a boundary. Hence there is an opportunity to
include small emissions and intersectoral transactions. This technique has been used to calculate
emissions related with exports and imports, and is
technically termed as ‘multiregional input–output
analysis’ (Robbie et al. 2009). Uncertainties, however, may accumulate as sectors are aggregated
(Green Design Initiative 2008; Matthews et al.
2008b). The micro level implementation of EIOLCA is limited (Wiedmann and Minx 2007).
An integration of PA-LCA and EIO-LCA,
called EIO-LCA hybrid, is emerging as the state
of art technique in LCA. In this hybrid method,
small emissions are covered by PA-LCA, while

rest is taken up by EIO-LCA. This preserves
robustness of EIO-LCA model and provides accuracy to PA-LCA, thus increasing completeness,
flexibility, and reliability of estimates.
Greenhouse gas accounting
In order to keep account of the emissions along
the life cycle, the following structured framework
is suggested (WRI/WBCSD 2004; Carbon Trust
2007a, b; BSI 2008):
1. Selection of GHGs
2. Setting boundary
3. Collection of GHG emission data
Selection of GHGs
Selection of the set of GHGs covered in calculation depends on the guideline followed, the need
of carbon footprint calculation, and on the type
of activity for which carbon footprinting is being
done. For example, in a thermal power plant,
where CO2 is a predominant emission and other
gases are almost negligibly emitted, only CO2
emission measurement will be feasible whereas
for a cattle farm, CH4 , CO2 , and N2 O emissions
may be significant. Although some studies include
only CO2 emissions in carbon footprint calculations (Patel 2006; BP 2007; Wiedmann and Minx
2007; Craeynest and Streatfeild 2008) others include the six Kyoto gases (Bokowski et al. 2007;
Energetics 2007; T C Chan Center for Building
Simulation & Energy Studies/Penn Praxis 2007;
Garg and Dornfeld 2008; Good Company 2008;
Matthews et al. 2008b). All the guidance and
standards also direct to include all the long-lived
GHGs and not only CO2 . Kelly et al. (2009) calculated carbon footprints of Indianapolis city in
USA based on only two gases, CO2 and CH4 ,
which were measured. If carbon footprint is
viewed in context of climate change, Peters (2010)
argues that it must cover black carbon also.
Setting boundary
Boundary refers to an imaginary line drawn
around the activities that will be used for calculating carbon footprint. It depends on the objective

Environ Monit Assess

of footprinting and characteristics of the entity for
which footprinting will be done. Boundary must
be selected so as to represent the organization
based on legal, financial, or business control. In
case of joint ventures, the organization may take
responsibility of the fraction of the emissions for
which it is responsible, technically called as ‘equity
share’ or may consider all the emission sources
which are under its direct control, depending on
the need of carbon footprinting. Once the organizational boundary has been established, operational boundary is to be selected. Operational
boundary refers to the selection of the direct and
indirect emissions, which will be accounted for. To
facilitate convenient accounting, tiers or scopes
have been suggested (WRI/WBCSD 2004; Carbon
Trust 2007b; BSI 2008):
1. All direct emissions, i.e., onsite emissions
2. Embodied emissions in purchased energy
3. All indirect emissions, such as those associated with transport of purchased goods, sold
products, business travels, energy activities,
disposal of products etc., not included in tiers

Fig. 2 Boundaries for calculation of carbon footprint

I and II (WRI/WBCSD 2004; Carbon Trust
2007a, b; BSI 2008; CDP 2008; Matthews et al.
2008a, b; Strutt et al. 2008).
Figure 2 illustrates the three tiers in carbon footprint estimation. The tiers II and III both include
indirect emissions, but tier II refers to the emissions embodied in energy production or (and)
purchase, transmission, and distribution caused
by the entity under consideration, but end user
emissions are out of scope of tier II. Tier III
tends to cover all the embodied emissions within
the specified boundary. But tier III has vaguely
been defined and the most carbon footprint studies limit up to tier II as it becomes too complex
to estimate carbon footprint beyond tier II with
accuracy (CDP 2008; Dada et al. 2008; Matthews
et al. 2008a, b). Also, it is important to be ascertained that to what extent responsibility and
control over emissions can be made beyond tier II
(Lenzen 2001). For this reason most GHG accounting standards (PAS-2050, GHG protocol,
and other registries and consultancies based on
these) have kept tier III optional. Advancement

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in the tracking and management of emissions in
the supply chain is expected to promote tier III
accounting and reporting (Matthews et al. 2008b;
CDP 2009). Based on order of emissions covered,
carbon footprint has two components namely
“basic” or “primary” referring to carbon footprint
calculated from direct emissions and emissions
embodied in energy purchase, and “full carbon
footprint” when all direct and indirect emissions
are included (Carbon Trust 2007b; Lynas 2007).
Among 500 companies inquired worldwide, 72%
of the respondents report their GHG emissions
up to tier II (CDP 2008). But in many cases,
tier III contributes most significantly to the total
CO2 -e. Only for the biggest known emitters such
as thermal power plants, cement industries, and
transportation tiers I and II can cover 80% of total
carbon footprint. For most of other processes,
only 26% of total carbon footprint could be covered up to tier II (Matthews et al. 2008b). Hence
tier III estimation has been promoted to include
relevant sources (relevance can be decided on the
basis of size, risk exposure of GHGs, etc) and
deemed critical by the stakeholders (CDP 2008).
Inclusion of an additional tier IV to cover emissions exclusively related to delivery, use, and disposal of products is also proposed (Matthews et al.
2008b). As more and more organizations start
reporting complete LCA, a database can be developed through which average firm specific data can
be estimated to suite the purpose (Matthews et al.
2008b; Weidema et al. 2008). Inclusion of international trade in carbon footprint calculations has
also been suggested (Courchene and Allan 2008).
Emissions embodied in traded goods, if consumed
out of the country should be shared based on appropriate assumptions (Peters 2010). But drawing
boundary to estimate emissions related to trading
particularly the international trade may be tough.
Regarding natural systems and land uses, the
selection of boundaries and tiers are very unclear.
But studies are going on to estimate and identify different mechanisms operating in nature that
control GHG emissions. National GHG inventories have been accepted worldwide as a reference methodology to account for the GHGs
emissions from land use, land use change, and
forestry (IPCC 1996, 2006). Almost all the carbon
footprint studies focus on emissions; the amount

of GHG removal and sequestration appears neglected (Peters 2010). These factors must be included in calculations.
Collection of GHG data
GHG data can be collected through direct onsite real-time measurements, or through estimations based on emission factors and models. The
choice of appropriate method depends on the
objective (mandatory, voluntary, or for internal
management), credibility, feasibility as well as on
cost and capacity considerations. Emission factors and models are the most preferred and used
techniques. In general, for products, organizations, and events, emissions are calculated using
specific emission factors and models utilizing
data on consumption of fuels, energy, and other
inputs leading to emissions (particularly CO2 ).
Emission factors are available for a wide range
of industrial processes and land uses in GHG
protocol, PAS-2050, IPCC (2006), and countrywise emission factors have been developed in
many countries such as national inventories under
2007; WRI/WBCSD 2004). But verification is
required at different operational and geographical contexts. Hence region-specific emission
factors and models have been recommended
(WRI/WBCSD 2004; IPCC 2006). But for other
sources and fugitive emissions, direct measurements should be applied. Direct measurements
include optical, chemical, and biological sensors
such as photo acoustic infrared sensors or other
instruments and techniques like collecting gases of
interest in specially designed chambers and analyzing through IR spectroscopy for CO2 and gas
chromatography for all GHGs (USCCTP 2005;
Berg et al. 2006). These techniques have been
applied for ground-based measurements whether
static, mobile, or aerial. Eddy covariance or flux
towers have been utilized to measure flux covering the entire landscape (Velasco et al. 2005),
while cavity ring-down spectrometers have been
utilized in aerial measurements (Kelly et al. 2009).
Besides onsite measurement, secondary data
sources and databases are now available at global
level also. A database of CO2 emissions from
different countries has been developed under

Environ Monit Assess

global trade analysis project (GTAP; Dimaranan
2006). Other reliable data sources can be national
GHG inventories and other government offices
keeping the data of fuel and energy consumption,
International Energy Agency, UNDP etc. (Brown
et al. 2009). Low-cost real-time measurement systems are under development.
While direct measurements are more accurate
and are clearly prescribed in globally accepted
protocols, their cost and application may be prohibitive (WRI/WBCSD 2004). In such cases, indirect estimations may yield fairly accurate results
if developed or modified specifically for a particular region or sector. Customized tools relying
on direct measurements as well as on interpolation or expansion of observations to non measurable fluxes (i.e., emission factors and models)
have enhanced practicability for intended users
(USCCTP 2005). The GHG protocol customized
GHG calculation tools (WRI/WBCSD 2006), are
worldwide accepted guidance for customizing the
tools for calculating GHG flux so as to suit
the respective sector or entity. Besides these,
continuous GHG monitoring is going on and is
being expanded to get broad spatial coverage
(Sundareshwar et al. 2007). For this, advanced
measurement and monitoring systems (remote
sensing, geographic information system, optical
measurements etc.) are now being integrated with
individual GHG inventories so as to provide
comprehensive and uniform coverage (USCCTP
2005). Scientific community is operating terrestrial and oceanic observation networks to collect
GHG data worldwide. FLUXNET, the global
terrestrial observing network monitors CO2 , water vapor, and energy at more than 300 sites
(Sundareshwar et al. 2007). These systems cover
a very broad spatial area, but the monitoring locations in Asia and Africa are sparse and should be
increased in number in order to obtain a reliable
global data (Sundareshwar et al. 2007).
To overcome the reduction in accuracy of
ground-based monitoring network due to patchy
distribution, satellites have been launched to monitor sources and sinks of CO2 and other GHGs
with uniform coverage (Haag 2007). Japanese
satellite, “the greenhouse gas observing satellite”
launched in 2009 is monitoring GHGs, while joint
project of NASA and US Department of Energy

called “Vulcan” is quantifying CO2 emissions due
to fossil fuel burning in North America (Gurney
et al. 2009; Kelly et al. 2009). Remote sensing and
geographic information system are extensively in
use for large and relatively less accessible areas.
Chambers et al. (2007) have used landsat imagery
to quantify live and dead wood, litter, soil, and
shade for estimating carbon footprint of hurricane
Katrina at US coast. Such GHG data are useful in calculation of carbon footprint related to
natural phenomena and events (Chambers et al.
2007). GHG emissions and avoidance embodied
in use of renewable energy, recycling of waste, energy recovery from landfills, and other such good
management practices, are estimated through
prescribed mathematical relations (WRI/WBCSD
2005; IPCC 2006; BSI 2008).
All the flux measurements are recorded relative to a base year (may be a single year or an
annual average over a period of several consecutive years). Its choice depends on the objective.
In most inventories, 1990 has been set as base
year in lieu of commitment of reduction of CO2 -e
emissions at 1990 level under UNFCCC. Selection
of base year is crucial and must be made in such a
way that it clearly reflects the importance of structural and operational changes in emissions over
time. According to GHG protocol, the earliest
relevant point in time for which reliable data are
available should be chosen as a base year. Besides
this, reproducibility, verifiability, and systematic
documentation are essential attributes of data collection (Carbon Trust 2007b).
Regarding voluntary personal carbon footprinting, numerous carbon calculators are available online as well as from consultancies. All of
these calculators claim to be based on recommended guidelines, but rarely any two of them
yield similar outputs for the same set of inputs
(Padgett et al. 2008; Kenny and Gray 2008). This
questions the accuracy and credibility of such
calculators. Among hundreds of online calculators, some calculate domestic carbon footprint,
while others calculate carbon footprint related to
specifically travel, food, or other such activities
(Murray and Day 2009). Very few calculators indicate the use of indirect emissions under tier III.
There is no coherence among the input data required for different carbon calculators. Table 2


USA and





Climate change

gas calculator

Table 2 Description of parameters included in different online personal calculators

actual values
as inputs.
Difficult to
understand as
any range of
values have
also not been

CO2 /yr factors* are
but sources
are not
donation to
offset CF
included in


Conservation international
carbon calculator.


1: http://www.
Climate change carbon calculator. http://www.
3: Federal Aviation
Greenhouse gas calculator.


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Act on CO2



An inconvenient USA
truth carbon

footprint with
1. Energy information An inconvenient truth
included in
carbon calculator.
official energy
offsetting CF
statistics from US
is proposed
with Native
voluntary reporting
of Greenhouse gases
program fuel and
calculated CF
energy source codes
with national
and emission
2. GHG protocol
mobile combustion
DEFRA Act on CO2
sources of
carbon calculator.
energy, house
behavior also
included in
calculated CF
with similar

Environ Monit Assess






Table 2 (continued)



lifestyle and
included in

Green tariffs
and renewable
included in
Provides tips
on low carbon
calculated CF
with national


1. Stockholm

2. The National
Energy Foundation
3. The National
Office of Statistics


Carbon neutral
carbon calculator.
WWF carbon

Resurgence quick
carbon calculator.


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number of
required to
sustain life
with the
not mentioned
but sources
are given.
Basically an
offset seller
calculated CF
with national
and world
2. Stockholm
Environmental Institute
3. United States
Department of Energy
4. The Ontario
Ministry of Energy
of Canada
5. UK Environment
6. State Government
of Australia
7. Sightline Institute
8. Eshel and Martin


Carbonify carbon

Liveclimate carbon

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emissions are
also included
in calculation.
calculated CF
with national
and world
based on
emissions are
also included
in calculation.
calculated CF
with national



1. California Climate
Sacramento municipal
Action Registry 2005
Utility district,
Livegreen carbon
3. www.fuel
calculator http://calc.
4. WRI/WBCSD (2004)
5. Eshel and Martin
6. Pimental et al. (2005)
The nature conservancy
carbon footprint calculator.
3. US DoE;
4. Eshel and Martin
5. Pimental et al. (2005)


Solid cylinders corresponding to the parameters not included in the calculation have been omitted. Cells corresponding to the parameters not included in the calculator
have been left blank. *Based on distance travelled, fuel consumption, or time for which the vehicle runs








Table 2 (continued)

Environ Monit Assess

Environ Monit Assess

describes some of the online carbon calculators.
Incorporation of information technology to design a personal environmental tracker has been
proposed to increase accuracy of such calculators,
while household and device level monitoring using
specific sensors is gaining popularity in developed
world (Brewer 2008a, b).
Footprint calculation
The GHG data are translated into CO2 -e using conversion factors provided by IPCC (WRI/
WBCSD 2004; BSI 2008). Some organizations
report carbon footprint as carbon equivalent
(Wiedmann and Minx 2007), but based on widespread acceptance, CO2 -e is more popular. The
unit of carbon footprint varies according to entity under consideration. Carbon footprint for
individuals and dynamic processes is calculated
periodically, usually annually. Events such as conferences, fairs, sports events, etc. have one-time
emissions. Some entities have a combination of
both, like carbon footprint of a building is a onetime figure during construction phase, while periodic calculations are needed during the operation
phase. Therefore, the time dimension must be
mentioned so as to indicate clearly the time period
over which the emissions have been estimated,
or if it is a one-time emission. PAS 2050 gives
provision of sharing one-time emissions over operation phase. Regarding services such as travel,
post, search engines, etc. emissions are reported
over an appropriate service unit like CO2 -e per
flight, CO2 -e per hour of surfing, CO2 -e per post
per mile, CO2 -e etc. Natural processes are highly
complex and hence they may be said to have a
temporally as well as spatially “dynamic carbon
footprint”. Uncertainties in calculations must also
be mentioned while reporting carbon footprint
(Carbon Trust 2007b).
Following examples demonstrate dif ferent
approaches for carbon footprint calculations
1. Carbon footprinting of nations: Edgar and
Peters (2009) used multiregional input--output,
analysis coupled with the database GTAP including all the Kyoto gases to calculate per
capita carbon footprints of 73 nations for the

year 2001. The boundary covered construction activities, shelter, food, clothing, mobility,
manufactured products, services, and trade in
their analysis. Minimum carbon footprint was
observed for Bangladesh, Mozambique, and
Uganda (1.1 ton CO2 -e) and was maximum
for Luxembourg (33.8 ton CO2 -e) as measured over 100-year time horizon.
UNDP (2007) also reported per capita carbon
footprint for nations for the year 1990 and
2004, but they include only CO2 emissions
arising from fuel combustion and cement production. The estimate showed United Arab
Emirates leaving the biggest footprint with
34.1 ton CO2 and smallest by India (1.2 ton
CO2 ). Carbon footprint of India as reported
in Edgar and Peters (2009) is 1.8 ton CO2 .
This clearly shows the difference due to variations in boundaries and GHG selections.
Some studies take into account the regional
details for producing a better picture of footprinting, but important issues of concern in
such comparisons are international trade related to exporting or importing countries, the
emissions embodied in manufacture, transport etc. (Peters 2010). Other economic situations, including parity in purchasing power of
the consumers, is also suggested to be counted
(Herrmann and Hauschild 2009).
2. Carbon footprint of large areas: studies have
been conducted to indicate the energy intensiveness and lifestyle of metropolitan cities
with the help of carbon footprinting. Brown
et al. (2008) estimated carbon footprint of
100 metropolitan areas in the USA based on
CO2 arising only due to fossil fuel combustion in transport and electricity consumption
in homes. Lebel et al. (2007) included CH4
and black carbon along with CO2 in comparative carbon footprinting for five metropolitan
cities of southeast Asia from 1980 to 2000 and
found that per capita emissions were comparable in all the selected cities. Their selection of gases and particulate carbon tends to
include all carbon-based emissions that have
warming effect. Sovacool and Brown (2010)
extend the boundary to include emissions
from agriculture and waste, wherever applicable in addition to tiers I and II that include

Environ Monit Assess

direct and indirect emissions in transport,
industries, and buildings. They also include
the emissions associated with goods manufactured within the city boundary, irrespective
of their point of use. In lack of single GHG
database, different data sources have to be
utilized thus making the studies difficult to
compare. As the secondary data sources may
have large uncertainties associated, or they
cannot be used in certain conditions, actual
measurements have to be carried out. Kelly
et al. (2009) collected data on CO2 and CH4
in planetary boundary layer over the region of
Indianapolis through aircraft-based measurements. Such measurements can measure the
overall net release of GHGs over a larger area
when interpolated through Kriging technique.
Fluxes were calculated through mass balance
approach. The uncertainties in their study
were due to wind speed. If still larger spatial
scale is to be covered, satellite data can be utilized. Utilizing LANDSAT and MODIS imageries, Chambers et al. (2007) projected the
amount of CO2 released during the decomposition of litter generated and change in sink
capacity due to the devastation caused by the
hurricane Katrina and calculated the carbon
footprint by utilizing the Monte Carlo model.
As a legal requirement, Good Company
(2008) carried out the GHG inventory for
the city of Vancouver deriving methodologies from The Climate Registry and a software program of International Council for
Local Environmental Initiatives under Cities
for Climate Protection campaign. The issues
which were not covered in these protocols
were analyzed independently. Choosing 2006
as the baseline year, inventory was designed
to cover three tiers. Tiers I and II covered
direct emissions resulting from equipments
and other operations under control of the
city, and GHG embodied in electricity, heat,
and steam, respectively. All the other indirect
emissions from institutional activities, business air travel, landfills, solid waste generation, and commutation of public were covered
under the tier III. Emissions covered under
tier III left the biggest footprint, but the precision of the data was also lowest.

It is clear that sink capacity has been considered in scientific studies, and carbon footprint
is being used as an environmental indicator
rather then a pressure indicating term. Incoherence in selection of gases is also clear from
these studies. It is important to give a careful consideration to the socioeconomic status, cultures, consumer behavior, and lifestyle,
while comparing such studies because such
reports form the basis of climate agreements.
3. Carbon footprints of academia: carbon footprinting for universities, schools, and similar institutions are going on. University of
Pennsylvania got its carbon footprint calculated by T C Chan Center for Building Simulation & Energy Studies/Penn Praxis (2007).
All the three tiers were defined to cover
almost all possible emissions inside the university (energy use in buildings and equipments, GHG releases from agricultural farm
and waste, employees and student’s commutation, and business flights etc.). The calculation tool, derived from an organization called
‘Clean Air Cool Planet’ was based on IPCC
(2006) and covered all the Kyoto gases. The
calculations were based on emission factors
from secondary data sources (records of the
university). The carbon footprint as calculated
for the year 1993 was approximately 3.5 ×
105 ton CO2 -e. As a result of partial GHG
offsetting through wind-generated power, the
carbon footprint reduced to 2.5 × 105 ton
CO2 -e in 2006.
4. The University of British Columbia and the
Simon Fraser University adopted the methodology outlined by ‘American College &
University Presidents’ Climate Commitment’
involving all the three tiers and all the GHGs
for footprint calculations (Ferris et al. 2007).
The calculated carbon footprint for University of British Columbia was 8.275 × 104 ton
CO2 -e. In Universities, tier II emissions were
found to be the highest. All of these studies
calculate carbon footprints based on emission
factors utilizing secondary data. Other type
of analysis that has been used in such cases
is EIO-LCA as carried out by Garg and
Dornfeld (2008) for carbon footprinting of
Kresege Engineering Library at University of

Environ Monit Assess

California, Berkeley. Estimations of energy
consumption in electronic equipments, GHGs
embodied in infrastructure and publication
and transport of books, CDs, periodicals,
and other documents to the library and employee’s commutation, were based on those
estimated by the researchers at University of
California, which yielded an annual carbon
footprint of 1.172 × 104 ton CO2 -e. (Garg and
Dornfeld 2008). PA and EIO LCA were integrated in a model called Resource and Energy
Analysis Program developed by Stockholm
Environment Institute, York, to estimate CO2
emissions from schools of UK, covering the
three well-defined tiers (Global Action Plan
5. Events: for London Olympic games 2012,
expected carbon footprint is under calculation (London 2012, Sustainability Plan 2007).
In lack of any proper guideline for GHG
accounting for large public events, the study
selected the GHG protocol. The tiers are not
classified according to the order of emissions
(direct and indirect), but according to the responsibility of the London 2012 Organizing
Committee of the Olympic and Paralympics
Games (LOCOG) over the emissions. In direct emissions, the activities funded fully by
LOCOG (construction of venue, office, and
utilities and the share of emissions for which
the games are responsible in jointly owned
facilities) have been covered. Other joint activities that include transportation, infrastructure, and upbringing of Olympic village have
been dealt separately. The third tier covers
for all the other associated activities, not
funded by LOCOG, but is attributable to the
games. This includes activities of media, sponsors, and visitors. Beyond this, the control of
LOCOG will be negligible; however, the associated emissions can be important. However,
accounting for those will make the study too
complex and uncertainties will also be high.
6. Carbon footprinting for individuals and households: individual and household carbon footprint calculators have surged the internet.
Despite of their claim to be based on globally
accepted protocols and emission factors, they
yield different results (Kenny and Gray 2008;

Padgett et al. 2008; Murray and Day 2009).
The disparity among them has been illustrated
in Table 2. Besides these commercial calculators, certain scientific studies have also been
conducted. Druckman and Jackson (2009)
classified the selected households in UK according to their socioeconomic status through
Local Area Resource Analysis model, based
on the input data of expenditure, fuel use,
and census. The authors focused to analyze
the change in carbon footprint as the status of
living is modernized. Using the MRIO model,
it was observed that in high level of functional
needs, highest share in carbon footprint was
of recreation, leisure, and personal air travels.
It is important to note that this study counted
only CO2 , covering up to tier II.
7. Carbon footprinting of corporations: any national or international climate agreement will
put direct pressure on businesses to cut their
carbon, owing to their biggest share and capability. Predicting the stricter carbon norms,
fine returns in the form of incentives for emission reductions, and consumers preferences
for products with low GHG contents, businesses have started to count and then cut
their emissions. Around 475 world’s largest
companies revealed their carbon footprints
in CDP (2009). About 83% of the participating companies disclosed carbon footprint
for tiers I and II only. Total tier III emissions of 5.8 × 109 ton CO2 -e were much higher
than combined emissions of tiers I and II
(0.6 and 3.6 × 109 ton CO2 -e, respectively).
The total direct GHG emissions under CDP
together contributed 11.5% of total global
emissions. Companies are therefore taking actions to reduce their carbon footprints. Ford
and Chrysler joined the US Climate Action
Partnership to cut emissions, whereas Google
and Dell decided to take steps to go carbon
neutral (Kleiner 2007).
Carbon footprints of food: like commodities,
separate carbon calculators have appeared online to calculate the footprints related to the
dietary habits. As food habits are directly
related to the culture, geography, etc., food
carbon footprint is very crucial. Pathak et al.
(2010) selected common Indian food items

Environ Monit Assess

and considered the relevant GHGs (CO2 ,
CH4 , and N2 O) associated with production
of raw materials, processing, transportation,
and final preparations for calculating carbon
footprint. Their calculations utilized the emission factors and data from NATCOM (2004),
MoA (2006), Pathak and Wassmann (2007),
and Pathak et al. (2009a, b). It was found that
the biggest footprint taking all the food items
was at production stage (87%), and maximum contribution was made by CH4 (71%).
An average non-vegetarian diet had high carbon footprint (1.031 × 10−3 for adult male
and 8.918 × 10−4 ton CO2 -e for adult female)
over the vegetarian (7.23 × 10−4 for adult
male and 5.838 × 10−4 ton CO2 -e for adult
female). A comparison between the online
food carbon footprint calculators by Kim and
Neff (2009) revealed that the inputs as well
as scopes for different calculators varied. The
calculations were based on different sources,
some of whom were also misapplied by calculators. Emissions avoided by shifting to organic or locally grown foods add a challenge
quantifying diet-related emissions accurately.
Most of these calculators calculate carbon
footprint of food based on Eshel and Martin (2006). They used FAOSTAT (2005) to
estimate the food exports and emission factors were derived from different studies. GHG
emissions associated with agriculture, and
transportation of variety of vegetarian and
animal-derived food items were estimated,
covering CO2 , CH4 , and N2 O. With objective of achieving GHG emissions associated
with individual diets, different combination of
food items were made to prepare hypothetical average diets and the carbon footprints
were calculated. Their study illustrated that
counting only CO2 cannot produce a realistic
carbon footprint as inclusion of other GHGs
made many food items distinct, which otherwise were of similar energy intensity.
A wide range of carbon footprinting studies,
involving corporate, governments, institutions,
and households are available, although there is
prevailing differences in boundaries, gases, and
methodologies selected for these calculations. In-

creasing carbon footprinting at all the areas of life
indicated that we have started recognizing our
responsibilities towards environment. Many of
them are a part of legal or voluntary emission
reduction targets, which is an appreciable act.
Carbon footprint has emerged as a strong mode
of GHG expression. While earlier studies focused
only on CO2 emissions as the guidelines and
suggested inclusion of all the important GHGs
in calculation, carbon footprint started becoming
synonymous to a comprehensive GHG account,
over the life cycle stages of any product or activity.
No definition, however, has yet been accepted
coherently as is clear from the fact that there
are different selection of gases and tiers among
studies. However, as carbon footprint reports are
increasing in response to legal or business requirements, most of the calculations are following the
GHG protocol worldwide. Since it has been extended to cover natural system as well, it becomes
essential to deal with the unavoidable emissions.
Carbon footprint has been commercialized and
is being utilized by organizations to count their
carbon and adopt measures to cut down emissions.
This business sense has taken carbon consciousness to the households through numerous online
calculators and has helped in making the civil
society aware of how much their activities are
contributing to global warming. Ironically, there is
no check on such carbon calculating facilities and
they lack coherence and transparency. Since carbon footprinting is associated with money transactions and has been found to influence businesses,
legal guidelines are necessary to monitor these
calculations. Carbon footprinting must be harnessed as a strong tool to promote GHG emission
reductions among businesses, events, and civil
society and should be included as indicator of
sustainable development.
An inconvenient truth, Carbon Calculator (2009). http://
Accessed 11 Sept 2009.

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Bellassen, V., & Leguet, G. (2007). The emergence of voluntary carbon of fsetting. Mission Climate Research
Report No. 11. Paris: Caisse des depots.
Berg, W., Brunsch, R., Hellebrand, H. J., & Kern, J. (2006).
Methodology for measuring gaseous emissions from
agricultural buildings, manure, and soil surfaces. In
Workshop on agricultural air quality, 5–8 June 2006,
Washington, DC.
Bokowski, G., White, D., Pacifico, A., Talbot, S., DuBelko,
A., Phipps, A., et al. (2007). Towards campus climate
neutrality: Simon Fraser University’s carbon footprint.
Simon Fraser University.
BP (2007). What is a carbon footprint? Available online
what_on_earth_is_a_carbon_footprint.pdf. Accessed on
7 Aug 2007.
Brewer, R. S. (2008a). Literature review on carbon footprint collection and analysis. Available online at http://
Accessed on 29 January 2009.
Brewer, R. S. (2008b). Carbon metric collection and analysis with the personal environmental tracker. In Workshops proceedings. UbiComp 2008, 21–24 September
2008, Seoul.
Brown, M. A., Southworth, F., & Sarzynski, A. (2008).
Shrinking the carbon footprint of Metropolitan
America. Washington, DC: Brookings Institute Metropolitan Policy Program.
Brown, M. A., Southworth, F., & Sarzynski, A. (2009). The
geography of metropolitan carbon footprints. Policy
and Society, 27, 285–304.
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